1. Technical Field
The present invention relates to a technique of a workpiece transfer apparatus that includes a workpiece transfer mechanism configured to transfer a workpiece inside a vacuum chamber, a base member that rotates the workpiece transfer mechanism from outside of the vacuum chamber, and a vacuum seal unit configured to seal a gap between the workpiece transfer mechanism and the base member.
2. Background Art
With reference to the workpiece transfer apparatus configured as above, a technique of cooling the workpiece transfer mechanism to thereby suppress the influence of radiant heat from the heated workpiece has conventionally been known. For example, such a technique is disclosed in Patent document 1.
According to Patent document 1, the vacuum seal unit (rotating base) configured to seal a gap between the workpiece transfer mechanism and the base member includes an air pump and a cooling circuit (cooling flow passage), routed from the pump into and then out of the workpiece transfer mechanism, using seal rings or the like. With such a configuration, air sent from the air pump flows through the cooling circuit, thereby cooling the workpiece transfer mechanism.
However, in the technique disclosed in Patent document 1, air is used as a coolant. Air has a specific heat capacity lower than that of water. Accordingly, as compared with the case where a liquid such as water is used as a coolant, there is a problem that cooling effect for the workpiece transfer mechanism may be insufficient.
In order to use a liquid such as water as a coolant, for example a configuration shown in FIG. 10A may be adopted. FIG. 10A depicts a vacuum seal unit 500 configured to seal a gap between a workpiece transfer mechanism 20 and a base member 10, in which a cooling pipe 510 (cooling flow passage) that allows a liquid to flow therethrough is routed from a pump (not shown) into and out of the workpiece transfer mechanism 20 inside a rotating shaft 520 that rotates the workpiece transfer mechanism 20. With such a configuration, the workpiece transfer mechanism 20 can be cooled by making the liquid fed from the pump flow through the pipe 510.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2007-118171.
However, with the configuration shown in FIG. 10A, when the workpiece transfer mechanism 20 is made to rotate, that is, when the rotating shaft 520 rotates, the cooling pipe 510 is twisted as shown in FIG. 10B. The twist of the cooling pipe 510 leads to the drawback in that the angle of rotation of the rotating shaft 520 is restricted, and hence the angle of rotation of the workpiece transfer mechanism 20 is restricted.
The present invention has been achieved in view of the above problems. An object of the present invention is to provide a workpiece transfer apparatus that can cool a workpiece transfer mechanism by use of a liquid such as water as a coolant and can prevent the angle of rotation of the workpiece transfer mechanism from being restricted.